@dragonice69 Hello, just to be sure we are talking of the same thing.
What I did is I selected the Volume Scatter option in the world tab, within the Volume section, I then adapted my settings.
For the swirls in the fog, It’s just a picture I overlayed in compositing.
Finally, the render time was huge on my computer, something like 1d and 20 h…
Therefore I used the free renderfarm sheepit to render my picture, there It took something like 1h30 maybe 2, I can’t remember.